Lapping tool



Patented Feb. 1, 1944 LAPPING TOOL Foster F.

American Steel Hiliix, Lakewood. Ohio, more The and Wire Company of New 1 Jersey, a corporation of New Jersey No Drawing.s

ZClaims.

This invention relates to lapping tools and the like, and more particularly to "finishing laps for finishing and polishing hard metal objects such as metal-working rolls and the like.

It is a prime object of my invention to provide such a tool having the characteristics of being friable while having sumcient strength to prevent a body or block thereof from breaking up in service, and being further characterized by the capacity to erode away evenly and at a sumcient rate to properly distribute and apply an abrasive grain over the surface of the work bein l p I have discovered that lead and mercury compositions or alloys possess the aforesaid characteristics to a high degree, and that a lap molded therefrom affords a speedy and efficient tool in practice. In experimenting with said composition, I have found that the mercury content.

thereof should preferably not be less than about 28% by weight, and that the action of a lap formed therefrom is still further enhanced by increasing the mercury content up to about from 35% to 87% by weight, the balance thereof being lead.

However, in excess of 87% of mercury with Q the lead produces a crumbly composition which will not remain in molded form in use, and therefore isunsuitable for a lapping tool.

An excellent composition and lap thereof which has proved highly satisfactory upon hardened steel metal-working rolls embodies about 35% mercury and 65% lead, by weight. A block or lapping tool molded therefrom is sumciently friable to provide a working face which has the desired porosity and erosion capacity to properiy accommodate and apply an obvious grain for producing line highly polished finishes.

Application August 15, 1942, erial No. 454,994

In actual test, such a lap produced a finish upon a 10-inch x 10-inch roll in approximate y thirty minutes. After use, the face of the lap showed no concentrated loading of the grain, and the surface of the roll was ,free of stray scratches or digs, the latter being the ruination of many an otherwise well lapped finish. The finish so produced upon the roll surface was highly polished with a desired uniformity.

The lap of my invention is simple and relatively inexpensivein comparison with laps employing more complicated alloys or compositions, and has the further attribute of being readily and selectively varied within the ran e specified 5 to produce compositions most suitable to a speciflc abrasive grain size or fineness.

Various changes and modifications contemplated within the scope of the following claims.

Iclaim:

l. A finishing lap consisting of about 28% to 37% mercury by weight and the balance thereof of lead. molded into block form, characterized by being friable and having the capacity to erode away evenly, while having sufficient strength to remain in molded form and to thereby apply a cutting pressure to abrasive grain.

2. A finishing lap consisting of about mercury and lead by weight, molded into so block form, characterized by being friable and 

